In a vehicle, the battery or other power system of the vehicle provides a power supply to various electronic accessories. The accessories may include, for example, accessories relating to engine performance, safety features, comfort features, and any other type of vehicle subsystem. Various conditions may impact the ability of the power system of the vehicle to deliver power to the accessories. For example, external conditions such as the driving environment around the vehicle may impact vehicle performance. Conditions such as the road the vehicle is driving on, the speed limit on the road, the traffic around the vehicle, and the weather may impact the power system, as the power required to operate the accessories in the conditions may vary. For example, when traveling uphill or in heavy traffic conditions, more power may be required to be focused on more critical vehicle subsystems, rather than systems like the HVAC unit. Further, there may be some conditions in which one or more accessories or subsystems may be able to advantageously produce an energy supply for the power system.